Mandrel for making inner tubes for pneumatic tires.



J. A. McTAGGART.

MANDREL FOR MAKING lNNER TUBES FOR PNEUMATIC TIRES.

APPLICATION FILED JAN. 21, 1917.

1,260,275. Patented Mar. 19, 1918.

JOHN A. MGTAGGART, OF PHILADELPHIA, PENNSYLVANIA.

MANDREL FOR MAKING INNER TUBES FOR PNEUMATIC TIRES.

Specification of Letters Patent.

Patented Mar. 19, 1918.

Application filed January 27, 1917. Serial No. 144,810.

To all whom it may concern: I

Be it known that 1, JOHN A. MOTAGGART, a citizen of the United States, and a resident of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in the Mandrels for Making Inner Tubes for Pneumatic Tires, of'which the following is a specification.

The principal object of the present invention is to provide for incorporating the valve fitting in the inner tube during its manufacture and prior to its vulcanization so that during the latter process the rubber material of the tube makes a close and excellent fit and joint with the contracted portion of the valve fitting, thereby not only facilitating and cheapening the manufacture but also providing improved inner tubes.

Generally stated the invention'consists of the improvements to be presently described and finally claimed.

In the following description reference will be made to the accompanying drawings, in which A Figure 1, is a View with parts broken away of a mandrel embodying features of the in vention.

Fig. 2, is a plan view of a part of the mandrel.

Fig. 3, is a view, drawn to an enlarged scale, illustrating partly in section and partly in elevation how the material of the inner tube after vulcanization makes a tight joint with the contracted portion of the valve.

Fig. 4, is a top or plan view, partly in section, of a valve fitting, and

Figs. 5 and 6, are views illustrating a modification.

In the drawings, 1 is a mandrel annular in form and circular in cross-section. It is shown to consist of three segments of which two, 2 and 3, are relatively short. The section 3 is detachably connected with the sections 1 and2 by dove-tail connections 4, and the section 2 is detachably connected with the section 1 by a dowel-pin connection 5.

6, is a cavity formed in the mandrel in the present instance in the section 2 thereof and it is adapted to receive the head 7 of the valve fitting and hold the valve fitting projecting radially of the annular mandrel 1, with the contracted portion 7 in exposed position. The cavity 6 not only holds the valve fitting in projecting position, as has been described, but also permits the head of the valve fitting to be lifted out of the cavity and so be detached from the mandrel.

In Figs. 5 and 6, the cavity 6 is adapted to receive the stem 8 of the valve fitting and hold it in such position that the contracted portion 7 is exposed. Two parts, 9 and 10, of the mandrel may be detachably held together as by dowel-pins 11, and the joint between these parts 9 and 10 is, at the cavity 6 so that when the parts are disconnected the valve fitting can be removed by a motion of rotation.

Having described novel apparatus adapted for the practice of the method of the invention, I will now proceed to describe the method of using the same.

The parts of the mandrel shown in Fig. 1 are assembled and the valve fitting arranged in the cavity 6. The tube is then formed I around the mandrel with the valve in place through the wall of the tube, which surrounds the contracted portion 7 a of the valve fitting. In using the mandrels of Figs. 5 and 6, this same step is practised. The next step is to vulcanize the tube with the valve fitting in place through the wall of the tube. Thereafter the tube having been vulcanized with the valve fitting in place in its wall, is removed and, referring to Fig. 1, this is done by slitting the tubes circumferentially, for example, along the part 3 of the mandrel, which part 3 is then removed. The head of the valve fitting is then lifted out of the cavity 6 and the section 2 of the manslit previously formed therein. Thereafter the section 1 of the mandrel is worked out through the slit in the tube.

In connection with Figs. 5 and 6, one of the parts, for example, the part 10 of the mandrel, is worked out of the tube which can be turned inside out for the purpose. The part 10 is removed from the part 9 and the tube removed in a similar way from the part 9 of the mandrel, so that the valve fitting turns out of the cavity 6*, or more accurately, out of the part of the cavity 6 that is formed in the part 9 of the mandrel. The tube, vulcanized, with the valve fitting in place having been removed from the mandrel the slit is appropriately closed. Durin the vulcanization the material of the is provided with a valve stem cavity into tu e as it softens, flows and makes a tight and out of which a valve stem can be lifted. 10 joint as indicated at a in Fig. 3 with the 2. Apparatus for making inner tubes for contracted portion of the fitting. pneumatic tires Which comprises an annular 5 What I claim is: mandrel consisting of detachable sections of 1. Apparatus for making inner tubes for which one is provided with a valve holding pneumatic tires comprising a mandrel concavity.

'sisting of detachable sections, of which one JOHN A. MOTAGGART. 

